A bimetallic strip is a device made of two different metals bonded together. When heated or cooled, the two metals expand or contract at different rates, causing the strip to bend. This bending can be used in various applications, such as in thermostats and temperature sensors. The principle behind a bimetallic strip relies on the differing thermal expansion coefficients of the metals involved. Common metal pairs include steel and copper or brass. This simple yet effective mechanism allows for the automatic regulation of temperature in many household and industrial devices.